Relationship Between Obesity and Early Failure of Total Knee Prosthesis
Relationship Between Obesity and Early Failure of Total Knee Prosthesis
Background: Obesity is a risk factor for knee arthritis. Total knee arthroplasty is the definitive surgical treatment of this disease. Therefore, a high percentage of subjects treated are overweight. Since 2000 in the Emilia-Romagna Region the Register of Orthopedic Prosthetic Implantology, RIPO, has recorded data of all the primary and revision operations performed on the knee; height and weight of patients at the time of surgery have also been recorded.
Methods: To understand how overweight and obesity affect the outcome of knee arthroplasty, a population of subjects treated with cemented total knee arthroplasty between 2000 and 2005 was studied. 9735 knee prostheses were implanted in 8892 patients; 18.9% of the patients were normal weight, 48.2% were overweight (25 < Body Mass Index ≤ 30), 31.1% were obese (30 < BMI ≤ 40), and 1.8% were morbidly obese (BMI > 40). Mean and range of follow-up were respectively 3.1 and 1.5-6 yrs. Implant failure was defined as the exchange of at least one component for whatever reason.
Results: In normal weight patients there were 36 failures out of 1840 implants (1.96%), in overweight patients there were 87 out of 4692 (1.85%), in obese 59 out of 3031 (1.94%), and in morbidly obese there were 4 out of 172 (2.3%). The mean time to failure for each class was 1.57, 1.48, 1.60, 1.77 yrs. Cox regression analyses showed that the risk of implant failure was not influenced by BMI, absolute body weight, or sex. Conversely, an increased failure risk was observed in mobile meniscus prostheses in comparison with those with a fixed meniscus (Rate Ratio 1.88); an increased failure risk was also related to age (Rate Ratio 1.05 per year). These results were also confirmed when considering septic loosening as the end-point. There were no differences in the rate of perioperative complications and death in the 4 classes of BMI.
Conclusion: In conclusion, cemented knee prostheses, implanted in patients with arthritis do not have significantly different rates of survival or perioperative complications in obese subjects compared with normal weight subjects, at least up to 5 years after surgery. The conclusion also applies to subjects affected by morbid obesity, altough this findings should be regarded with caution due to the small sample examined.
The prevalence of obesity in industrialized and emerging countries is reaching epidemic proportions. The growth of the population with an unhealthily high body weight is particularly relevant in the USA where 71% of the inhabitants over 60 years old are overweight or obese, although it has reached warning levels in many European countries and Australia.
In Italy obesity is a public health problem: 39% of women and 50% of men over 65 of age are overweight and 15% and 14% respectively are obese. In the Emilia Romagna Region, in the North of the Country where most of the population considered in this study live, in the same age range, 42% of women and 55% of men are overweight and 13% and 14% are obese.
Obesity is related to several cardiovascular, metabolic, and osteoarticular diseases, especially arthritis of the knee and hip, and also other joints bearing smaller loads, thus suggesting both a mechanical and biochemical role in articular degeneration. Treatment of arthritis is initially conservative using drugs and physiotherapy, but often, as the disease progresses, total joint arthroplasty becomes necessary. Therefore, many obese subjects can be found among those treated by total joint arthroplasty and the correlation between BMI (Body Mass Index) and osteoarthritis is now clear. Oliveria demonstrated that the risk of symptomatic osteoarthritis of the knee increased dramatically with increasing BMI (3.8 for BMI up to 30 and 9.3 for BMI > 30). Similarly, each unit in age-adjusted BMI has been shown to be associated with a 4% increase in incidence of osteoarthritis.
Based on these premises, the practice of knee joint arthroplasty is becoming more widespread worldwide and its efficacy is undisputed.
Besides clinical experience, all implant Registers starting from 1975, following the example of Sweden, have confirmed the excellent results of this surgical procedure. In Italy RIPO (Register of the Orthopedic Prosthetic Implantology) began in 2000 in Emilia Romagna, a region counting 4.500.000 inhabitants; it captures 95% of the operations either primary and revision performed in the 61 public and private health structures of the Region. Revisions undertaken in other regions of Italy are included, because the economic compensation among administrative services of Italian regions allows RIPO not to lose these patients to follow-up. Even if good results are generally obtained with total knee arthoplasy (TKA), some authors have raised doubts about its effectiveness in obese subjects, so much so that recently the East Suffolk Health trust prioritized non-obese (BMI < 30) in the selection of patients for lower limb joint replacement surgery.
The scientific community does not fully agree with this choice since there is no clear and definitive evidence of the effectiveness of the operation in obese patients. The literature, in fact, mainly shows the data of limited series, which do not provide a unanimity of views, both with regards to the different endpoints used in the definition of success, and the different stratifications performed in the patients.
The purpose of the present study was therefore to try to fill this gap and examine the relationship between body mass index and survivorship of knee prostheses on a register-based data-set.
Abstract and Background
Abstract
Background: Obesity is a risk factor for knee arthritis. Total knee arthroplasty is the definitive surgical treatment of this disease. Therefore, a high percentage of subjects treated are overweight. Since 2000 in the Emilia-Romagna Region the Register of Orthopedic Prosthetic Implantology, RIPO, has recorded data of all the primary and revision operations performed on the knee; height and weight of patients at the time of surgery have also been recorded.
Methods: To understand how overweight and obesity affect the outcome of knee arthroplasty, a population of subjects treated with cemented total knee arthroplasty between 2000 and 2005 was studied. 9735 knee prostheses were implanted in 8892 patients; 18.9% of the patients were normal weight, 48.2% were overweight (25 < Body Mass Index ≤ 30), 31.1% were obese (30 < BMI ≤ 40), and 1.8% were morbidly obese (BMI > 40). Mean and range of follow-up were respectively 3.1 and 1.5-6 yrs. Implant failure was defined as the exchange of at least one component for whatever reason.
Results: In normal weight patients there were 36 failures out of 1840 implants (1.96%), in overweight patients there were 87 out of 4692 (1.85%), in obese 59 out of 3031 (1.94%), and in morbidly obese there were 4 out of 172 (2.3%). The mean time to failure for each class was 1.57, 1.48, 1.60, 1.77 yrs. Cox regression analyses showed that the risk of implant failure was not influenced by BMI, absolute body weight, or sex. Conversely, an increased failure risk was observed in mobile meniscus prostheses in comparison with those with a fixed meniscus (Rate Ratio 1.88); an increased failure risk was also related to age (Rate Ratio 1.05 per year). These results were also confirmed when considering septic loosening as the end-point. There were no differences in the rate of perioperative complications and death in the 4 classes of BMI.
Conclusion: In conclusion, cemented knee prostheses, implanted in patients with arthritis do not have significantly different rates of survival or perioperative complications in obese subjects compared with normal weight subjects, at least up to 5 years after surgery. The conclusion also applies to subjects affected by morbid obesity, altough this findings should be regarded with caution due to the small sample examined.
Background
The prevalence of obesity in industrialized and emerging countries is reaching epidemic proportions. The growth of the population with an unhealthily high body weight is particularly relevant in the USA where 71% of the inhabitants over 60 years old are overweight or obese, although it has reached warning levels in many European countries and Australia.
In Italy obesity is a public health problem: 39% of women and 50% of men over 65 of age are overweight and 15% and 14% respectively are obese. In the Emilia Romagna Region, in the North of the Country where most of the population considered in this study live, in the same age range, 42% of women and 55% of men are overweight and 13% and 14% are obese.
Obesity is related to several cardiovascular, metabolic, and osteoarticular diseases, especially arthritis of the knee and hip, and also other joints bearing smaller loads, thus suggesting both a mechanical and biochemical role in articular degeneration. Treatment of arthritis is initially conservative using drugs and physiotherapy, but often, as the disease progresses, total joint arthroplasty becomes necessary. Therefore, many obese subjects can be found among those treated by total joint arthroplasty and the correlation between BMI (Body Mass Index) and osteoarthritis is now clear. Oliveria demonstrated that the risk of symptomatic osteoarthritis of the knee increased dramatically with increasing BMI (3.8 for BMI up to 30 and 9.3 for BMI > 30). Similarly, each unit in age-adjusted BMI has been shown to be associated with a 4% increase in incidence of osteoarthritis.
Based on these premises, the practice of knee joint arthroplasty is becoming more widespread worldwide and its efficacy is undisputed.
Besides clinical experience, all implant Registers starting from 1975, following the example of Sweden, have confirmed the excellent results of this surgical procedure. In Italy RIPO (Register of the Orthopedic Prosthetic Implantology) began in 2000 in Emilia Romagna, a region counting 4.500.000 inhabitants; it captures 95% of the operations either primary and revision performed in the 61 public and private health structures of the Region. Revisions undertaken in other regions of Italy are included, because the economic compensation among administrative services of Italian regions allows RIPO not to lose these patients to follow-up. Even if good results are generally obtained with total knee arthoplasy (TKA), some authors have raised doubts about its effectiveness in obese subjects, so much so that recently the East Suffolk Health trust prioritized non-obese (BMI < 30) in the selection of patients for lower limb joint replacement surgery.
The scientific community does not fully agree with this choice since there is no clear and definitive evidence of the effectiveness of the operation in obese patients. The literature, in fact, mainly shows the data of limited series, which do not provide a unanimity of views, both with regards to the different endpoints used in the definition of success, and the different stratifications performed in the patients.
The purpose of the present study was therefore to try to fill this gap and examine the relationship between body mass index and survivorship of knee prostheses on a register-based data-set.